When an electronic mail (e-mail) message is sent, the intended recipients of the message are typically specified by listing their e-mail identifiers. For example, an e-mail address might be specified as "login-id@domain-name". Such an address uniquely identifies the recipient globally.
However, a need arises to specify the intended recipients of a message, not by their identities, but rather by properties associated with the recipients. For example, desired sets of recipients might be described by the properties: "company employees interested in databases", "company employees who work in New Jersey", "company employees interested in databases and who work in New Jersey", etc. Such property-based addressing is currently supported by two distinct mechanisms.
One prior art mechanism that supports property-based addressing is directory addressing. Use of a directory allows for the specification of a combination of attribute value pairs to select an intended set of recipients. The attribute names must be part of the directory schema. For example, a company e-mail directory of employees may have attributes indicating the state in which each employee works and the salary grade or title of each employee. Prior art systems allow the use of conjunctive specifications of the form "state=nj:t1=SGD", where "state=nj" specifies the state of New Jersey, "t1=SGD" specifies a title of "SGD" and ":" is the conjunction operator. Thus, this specification would indicate all company employees who work in New Jersey and who have a title of "SGD". Such a directory based addressing scheme is described in commonly-owned U.S. patent application Ser. No. 08/581,654 by Mark Jones, which is hereby incorporated by reference.
Another prior art mechanism that supports property-based addressing is mailing lists. Mailing lists are a mechanism for creating lists of identities of message recipients. Once a mailing list is defined, a message sender may select a set of intended recipients without actually knowing the identities of the recipients. For example, a mailing list designated "codb" may contain the identities of company employees interested in databases, and a mailing list "comsg" may contain the identities of company employees who are interested in messaging.
Current messaging systems are limited in that they do not support combinations of directory and mailing list addressing mechanisms, even though some current messaging systems support each mechanism separately. For example, it is not currently possible to specify that the intended recipients of a message are "company employees whose salary grade is SGD and who are members of the `codb` mailing list". A related limitation is that current messaging systems that support the use of mailing lists do not permit the specification of intended recipients using arbitrary combinations of individual mailing lists. For example, it is not currently possible to specify that the intended recipients of a message are "company employees who are in the intersection of the mailing lists `codb` and `comsg`".
Another limitation of current messaging systems is that membership in mailing lists must be explicitly enumerated, and cannot make use of directory information. For example, it is not currently possible to specify that members of the mailing list "ha6117" are "company employees whose organization code in the directory is HA6117000". This may lead to replication of information and potential inconsistencies in the information maintained.
A need arises for a technique which supports combinations of directory and mailing list addressing mechanisms, provides the capability to specify intended message recipients using combinations of mailing list and directory information and does not require mailing lists to be explicitly enumerated.